1. Field of the Invention
The present invention relates to a system for transmitting and receiving data in which a base station transmits image and audio data that is information on image and/or audio to a monitor and the monitor receives the image and audio data and reproduces and displays the received image and audio data; a transmission apparatus therefor; a reception apparatus therefor; and a method for transmitting and receiving such the data.
2. Description of Related Art
In recent years, as a kind of wireless LAN systems constructed within limited areas such as a house and an office, utilized has been a system for transmitting and receiving data which includes, in combination, a base device that serves as an information source or an access point, and a display terminal that acquires information from the base device through a wireless communication system with the base station and displays it. For example, the base device incorporates or is connected with a television tuner for receiving broadcast signal, and is connected with a telephone line via a modem.
The display terminal, for example, transmits a request for acquiring television image to the base device, or receives the television image from the base device. Further, the display terminal also transmits and receives electronic mails via the base device or receives information on the Internet. Then, the display terminal displays the received image and information on its display. The base device, when receiving the request for acquiring the television image from the display terminal, reads the television image from a storing device thereof, and transmits it to the display terminal. Further, when the base device receives from the display terminal, for example, a request for receiving electronic mails, the base device acquires the electronic mails from the mail server thereof and transfers them to the display terminal.
According to such the system for transmitting and receiving data, the display terminal is capable of acquiring information from the base device through wireless communication system, and accessing information on the Internet through the base device. In this manner, a plurality of display terminals can share one and the same base device, and as a result, they can share the same information and cost reduction is achieved.
FIG. 1 shows a configuration of a control system relative to a system 200 for transmitting and receiving data as related art.
A transmission apparatus 201 in the system 200 receives, for example, an image and audio broadcast signal such as a television broadcast signal via a television tuner 265. An AV encoder 202 then receives digital AV (Audio and Visual) data contained in the television broadcast signal and compresses the AV data according to a predetermined image and audio compression scheme. A storing device 206 receives the AV data from the AV encoder 202 via a PCI bus line 203, a Host PCI bridge 204, and a Host bus line 205, and stores it. At the same time, a DMA controller 207 performs any data transfer controls under a so-called bus master condition such that the CPU 208 can utilizes the bus lines preferentially to reduce the processing load to the CPU 208. The stored AV data is output to a PCI controller 209 via the Host bus line 205, the Host PCI bridge 204, and the PCI bus line 203. The PCI controller 209 then outputs the AV data to a protocol-processing section 211 via a PCI internal bus 210. The protocol-processing section 211 performs on the AV data any processing based on a predetermined communication protocol conversion.
The transmission apparatus 201 then converts the AV data converted due to the protocol to transmission data and transmits it as a radio signal to a reception apparatus 251 of the system 200 for transmitting and receiving data via a transmitting and receiving section 212 and an antenna 213. At this time, the transfer efficiency in the protocol-processing section 211 is about 30 Mbps at the maximum, for example, whereas the transmission efficiency in the transmitting and receiving section 212 is about 54 Mbps at the maximum.
The reception apparatus 251 receives the radio signal from the transmission apparatus 201 as reception data by a transmitting and receiving section 253 via an antenna 252 of the reception apparatus 251. The transmitting and receiving section 253 transfers it to a protocol-processing section 254. At the same time, the DMA controller 255 performs any data transfer controls under a so-called bus master condition such that it can utilizes the bus lines preferentially to reduce the processing load to a CPU 259. The protocol-processing section 254 converts the reception data into AV data. A storing device 258 then receives the AV data via a PCI internal bus 256, a PCI controller 257, a PCI bus line 262, a Host PCI bridge 261, and a Host bus line 260, and stores it. The stored AV data is transferred to an AV decoder 263 via the Host bus line 260, the Host PCI bridge 261, and the PCI bus line 262. The AV decoder 263 performs any extension processing on the AV data according to a predetermined image and audio extension scheme. As a result, an image and audio signal such as a television signal can be reproduced.
As to the base device equipped with the data transfer ability like the above-described case, Japanese Patent Application Publication No. 2003-289315 discloses a packet transfer device. The packet transfer device includes an Ethernet (trade name) controller, a wireless LAN controller, a CPU bus, a data bus, a bus bridge, a local memory, a buffer memory and a CPU. The Ethernet (trade name) controller and the wireless LAN controller directly connect the CPU bus. A header portion of the received packet is stored in the local memory on the CPU bus. The data portion of the received packet is stored in the buffer memory on the data bus. In this manner, direct access from the CPU, the Ethernet (trade name) controller, and the wireless LAN controller is enabled while bypassing the bus bridge. Further, since the data bus is independent from the CPU bus, the packet transfer performed on the CPU bus is not hindered by the transfer of the data portion, thereby reducing the time for processing the packet transfer.